A rule issued April 16, 2008, ostensibly to keep the public safe from shipments of highly hazardous materials by rail, has been little-understood by the public and little-covered by the media, although hundreds of thousands of U.S. lives are at stake.

And public understanding will only be hurt by the secrecy provisions in the rule, published in the Federal Register by the Department of Transportation's Pipeline and Hazardous Materials Safety Administration.

Every year, tens of thousands of shipments of hazardous substances like chlorine gas roll through densely populated U.S. cities. While none has ever been attacked by terrorists, some regularly cause injury because of accident, equipment failure, or operator error. Estimates of the number of deaths that could come from a chlorine tank car rupture range above 100,000.

In recent years, cities like the District of Columbia have sought to re-route rail hazmat shipments around populated areas. The federal government, at the urging of the rail companies, has resisted, and tried to deny even judges hearing the cases any information about the hazards rail hazmat presents. Cities have sought, largely in vain, to get information about rail hazmat shipments that would help their fire departments prepare for an emergency.

The Society of Environmental Journalists has opposed such secrecy.

The new rule, which as an "interim final" rule takes effect immediately, leaves it to railroads to determine what hazmat routes are safe and feasible, with only a minimal federal oversight or regulatory role.

The rule requires railroads to compile information about what hazmat shipments they are carrying and where they are being routed.

Under the rule, that information would not even be given to the Department of Homeland Security or the Department of Transportation - unless they ask for it. Moreover, the rule states: "Each rail carrier must restrict the distribution, disclosure, and availability of information collected or developed [under the rule] to covered persons with a need-to-know."

The rule also declares invalid any law passed by a state or locality that would prevent rail hazmat shipments from passing through their boundaries.